JPH06134613A - Removing method for inside bead of welded steel pipe and device therefor - Google Patents

Abstract

PURPOSE:To provide an inside bead removing method for improving the form of the inside weld bead part of a seam welded steel pipe. CONSTITUTION:An internal rolling roll unit having a rolling roll which can be moved in the dirction of pipe diameter by a hydraulic cylinder 24 is movably attached to the tip of a pipe inside bead cutting mandrel 20, and cooling water is introduced through the cooling water passage 20-1 of the mandrel 20. The outside of an electric resistance welded tube 1 is provided with a back up roll in a pair of the rolling roll 23. A pipe inside bead 6 is cut and removed by a cutting bite 21 at the tip of the mandrel 20, and the cut part of the bead 6 is then rolledly smoothed by the pipe internal rolling roll 23 and a pipe outside back up roll. Thus the seam welded steel pipe can correspond to the variation of its wall thickness, and the pipe inside rolling roll unit is prolonged in the life thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing an inner weld bead of a welded steel pipe (electric resistance welded steel pipe).

[0002]

2. Description of the Related Art As is well known for electric resistance welded steel pipes, a strip of raw material is continuously formed into a tubular shape by a group of forming rolls, and then both edges of an open pipe formed into the tubular shape are subjected to electric resistance welding. It is manufactured by heating and pressing. The weld beads generated on the inner and outer surfaces of this electric resistance welded steel pipe are processed by a method of cutting and removing with a bite or the like, but in particular for the pipe inner surface bead, in the case of electric resistance welded steel pipe where the inner surface shape and quality are important, It is necessary to pay attention to the bead cutting shape.

As a method of removing the bead on the inner surface of the electric resistance welded steel pipe, a method of inserting a mandrel with a bite attached to the tip into the pipe to cut and remove is generally used. It is difficult to make it smooth with the uncut base material without any step. Therefore, various means for improving the shape of the inner bead portion have been proposed.

Means for improving the shape of the inner bead portion are roughly divided into (1) a method of crushing the inner bead without removing it, and (2) a method of smoothing the inner bead removed portion with a roll. There are two.

As the method (1), there is known a method of crushing the inner beads with a roll (Japanese Patent Laid-Open No. 52-15).
6758, JP-A-56-109111, JP-A-56-109113, and JP-A-58-1996.
24). As a typical example thereof, the one disclosed in Japanese Patent Laid-Open No. 56-109113 is shown in FIG.
Shown in. This inner bead removing device rotatably attaches a pair of rollers 4 to a holder 3 attached to the tip of a shaft 2 inserted into an electric resistance welded steel pipe 1, and further moves vertically above and below the position where the rollers abut. This is a device in which a pair of backup rolls 5 are installed and the beads on the inner surface of the pipe are crushed by the rollers 4 to make them smooth.

As the method (2), as shown in FIG. 9, for example, the inner bead 6 of the electric resistance welded steel pipe 1 is scraped off by the shoe 7, and then the holder 9 is attached to the tip of the mandrel 8 inserted into the pipe. A method of rolling and smoothing the inner surface of the welded portion with a pressure roller 10 mounted via the method (see Japanese Patent Application Laid-Open No. 1-306176), as shown in FIG. 10, a tool holder with a cutting tool 11 mounted on the tip of the mandrel 8. A device for smoothing the inner bead cutting portion by attaching a rolling roll 13 to 12 and an outer rolling roll 14 facing the rolling roll 13 via a welded portion
No. 2-105712), etc. have been proposed.

[0007]

However, the above-mentioned conventional techniques have the following problems. That is,
The method of crushing the inner bead with a roll of (1) can smooth the welded portion, but in all of these methods, an inner bead containing a slag component such as an oxide is internally contained in the steel pipe itself. However, it is not suitable for applications in which strength and corrosion resistance are required because it has a structurally non-uniformity.

Japanese Unexamined Patent Publication No. 1-306, which adopts the method (2).
In the case of the inner bead removing method described in Japanese Patent No. 176, it is highly possible that (a) a part of the inner bead removed by the shoe is imprinted on the tube itself.
(B) Since the position of the pressure bonding roll is fixed, if the wall thickness of the steel pipe fluctuates, the effect of rolling changes, and if the wall thickness changes significantly, it is necessary to change the roll unit setup. (C) Since the cooling of the roll unit is not taken into consideration, the roll life and the sliding portion life are short, and there are drawbacks such as not being applicable to the production of hot-welded steel pipes.

Further, in the case of the weld rolling apparatus described in Japanese Utility Model Laid-Open No. 62-105712, since the rolling roll has an integrated structure with the bead cutting bite, fluctuations in roll position and vibration during pipe manufacturing. Has a drawback that the bead cutting on the inner surface is likely to be unstable, and similarly to the above, since the cooling of the roll holder is not taken into consideration, there is a drawback that the life of the roll, the rotating shaft, the bearing, etc. is short.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and can cope with a change in the wall thickness of the electric resistance welded steel pipe, stabilize the bead cutting on the inner surface, and improve the durability of the roll unit. An object of the present invention is to propose a method and an apparatus for removing inner beads of a welded steel pipe that can be improved and can be applied to the production of hot-welded steel pipe.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a roll for supporting an outer surface of a pipe after cutting an inner bead with a cutting tool and a rolling roll movable in a radial direction of a pipe by a fluid pressure cylinder arranged in the pipe are provided. The method of rolling and smoothing the cutting part is the main point, and as an apparatus for carrying out the method, a pair of or more of a movable body in the pipe radial direction by a fluid pressure cylinder is provided at the tip of the mandrel for cutting the bead on the pipe inner surface. A roll unit having a rolling roll is mounted via a swing mechanism, and the roll unit has a water-passing structure and a structure for supplying cooling water through the mandrel, and a backup roll is paired with the rolling roll of the roll unit. The gist is that the structure is arranged on the outer surface of the pipe.

[0012]

Since the welded portion is rolled after the bead on the inner surface of the pipe is cut, oxides such as slag contained in the inner bead do not exist inside the pipe.

Since the inner surface rolling roll is movable in the pipe radial direction by the fluid pressure cylinder, it is possible to cope with the fluctuation of the wall thickness of the pipe.

Since the pipe inner surface rolling roll unit is mounted on the mandrel with the inner surface cutting tool through the swinging mechanism, the influence of the roll unit fluctuation due to rolling does not appear in the inner surface bead cutting.

Since the pipe inner surface rolling roll unit has a water-cooled structure, the life of the rolls, rotary shafts, bearings and the like is improved, and it can be applied to the production of hot-welded steel pipes.

[0016]

1 is a side view showing an apparatus according to an embodiment of the present invention, FIG. 2 is a vertical sectional front view taken along the line A--A of FIG. 1, and FIG. 3 is an enlarged vertical sectional side view of the apparatus shown in FIG. FIG. 6 is a vertical cross-sectional side view showing an apparatus according to another embodiment of the present invention. 20 is a water-cooled mandrel, 21 is a cutting tool, 22 is a pipe inner surface rolling roll unit, 23 is a pipe inner surface rolling roll, and 24 is a small size. A hydraulic cylinder, 25 is a pipe outer circumference backup roll.

The water-cooled mandrel 20 has a cooling water passage 20-1 therein, and an inner bead cutting bite 21 is attached to the tip thereof. Tube inner surface rolling roll unit 2
2 is attached to the tip of the mandrel 20 via a connecting shaft 26 so as to be swingable in the pipe radial direction.

The pipe inner surface rolling roll unit 22 is divided into two chambers by a partition wall 22-1 as shown in an enlarged view of its internal structure in FIG. 3, and each chamber is communicated by a communication hole 22-2. . A small hydraulic cylinder 24 built in this roll unit is installed in the partition wall 22-1 in the pipe radial direction, and a pair of pipe inner surface rolling rolls 23 are installed on the same center line as this cylinder. Among the rolling rolls, the rolling roll 23 located on the welded part side is rotatably attached to the unit body by a shaft 23-1, and the rolling roll 23 located on the opposite side to the welded part is provided with a small hydraulic cylinder 24. 23-2 movably fitted in the chamber
Is rotatably attached to the shaft 23-3. 23-
4 is a communication hole. Reference numeral 27 is a unit cooling water passage communicating with the cooling water passage 20-1 of the mandrel 20, and the hydraulic pipe 28 of the small hydraulic cylinder 24 is connected through this passage.

The pipe outer peripheral backup roll 25 is installed so as to face each pipe inner surface rolling roll 23 of the pipe inner surface rolling roll unit 22.

In the above apparatus, the pipe inner surface bead 6 is continuously cut by the cutting tool 21 attached to the tip of the mandrel 20. The inner bead cutting portion is located in front of the cutting bite 21 and is a small hydraulic cylinder 2
4 is rolled by a rolling roll 23 pressed against the inner surface of the pipe and a pipe outer peripheral backup roll 25. The pipe inner surface rolling roll unit 22 includes a mandrel 2 via a connecting shaft 26.
Since the movable unit is movably connected to 0, fluctuations of the roll unit that occur during rolling of the inner bead cutting unit are absorbed by the movable connecting unit and do not affect the inner bead cutting. Further, in the pipe inner surface rolling roll unit 22,
Since the cooling water is constantly introduced from the unit cooling water passage 27 communicating with the cooling water passage 20-1 of the mandrel 20, the influence of the welding heat of the electric resistance welded steel pipe is extremely small.

Further, since the inner surface rolling roll 23 is movable in the pipe radial direction by the small hydraulic cylinder 24, even if the wall thickness of the electric resistance welded steel pipe is changed, the hydraulic pressure of the small hydraulic cylinder 24 is kept constant so that A certain rolling effect can be obtained.

FIG. 4 exemplifies a movable mechanism of a pipe inner surface rolling roll unit. A roll jig 31 is connected to a connecting jig 30 fastened to the tip of a mandrel 20 with a bolt or the like in a pipe radial direction by an uneven fitting method. It is movably connected. Three
2 is a cooling water pipe, which is a cooling water passage 20- of the mandrel 20.
It is connected to 1.

FIGS. 5 and 6 show an example in which a pair of pipe inner surface rolling rolls are provided. In the case of FIG. 5, there are two rolling rolls 23 located on the opposite side of the inner surface bead of the pipe inner surface rolling roll unit 33 having a one-chamber structure. 6 shows an example in which two pairs of rolling rolls 23 are provided. In this case, a small hydraulic cylinder 24 built in a pipe inner surface rolling roll unit 34 having a one-chamber structure is movably internally fitted. The rolling roller 23 on the inner bead side is axially supported by the bearing 34-1.

Although not shown in the drawings, in the present invention, it is also possible to adopt an arm system for the supporting means of the rolling rolls. In this case, the roll support arm can be supported by a small hydraulic cylinder so as to be movable in the pipe radial direction. Further, the hydraulic pipe of the small hydraulic cylinder 24 and the cooling water passage do not necessarily have to be shared, and the cooling water passage and the hydraulic pipe may have independent paths.

Example 1 The device of the present invention shown in FIGS.
4 mm, wall thickness 3.2 mm), and measurement results of bead lateral thickness deviation values when the rolling load of the inner surface rolling roll is variously changed are shown in FIG. 7. From the results of FIG. 7, it is apparent that the apparatus of the present invention can easily and satisfactorily smooth the inner bead cutting portion only by controlling the rolling load of the inner surface rolling roll.

[0026]

As described above, the present invention is a system for rolling and smoothing a welded portion after cutting by an inner surface rolling roll which is movable in a tube radial direction by a fluid pressure cylinder in a tube inner surface roll unit. Since a constant rolling effect can be obtained regardless of the wall thickness variation of ERW steel pipe, the inner bead cutting part can be smoothed well, and the pipe inner roll unit is attached to the mandrel via the swing mechanism. Fluctuation of the roll unit due to rolling does not affect the inner bead cutting, the inner bead cutting is stabilized, and the pipe inner surface roll unit has a cooling structure to improve the life of the entire roll unit. Excellent effect such as. Further, since the device of the present invention can be implemented by being attached to the tip of the mandrel for cutting the inner surface bead, there is an advantage that it can be easily applied to the existing electric resistance welded steel pipe manufacturing equipment. It greatly contributes to the improvement of the operating rate and the quality of ERW pipe.

[Brief description of drawings]

FIG. 1 is a side view showing an apparatus according to an embodiment of the present invention.

FIG. 2 is a vertical sectional front view taken along the line AA of FIG.

FIG. 3 is an enlarged vertical side view of the same device.

FIG. 4 is a vertical cross-sectional side view showing an example in which the pipe inner surface rolling roll unit in the same apparatus is movably provided by a concavo-convex fitting method.

FIG. 5 shows a pair of pipe inner surface rolling rolls in the same apparatus.
It is a vertical side view which shows the example comprised individually.

FIG. 6 shows a pair of tube inner surface rolling rolls in the same apparatus.
It is a vertical side view which shows the structural example provided in pairs.

FIG. 7 is a diagram showing the relationship between rolling load and bead lateral thickness deviation value in the example of the present invention.

FIG. 8 is a schematic side view showing an example of a conventional inner surface bead removing device that adopts a method of crushing inner surface beads of a pipe with a roller.

FIG. 9 is a schematic side view showing an example of a method of rolling and smoothing a welded portion with a pressure roller after removing the bead on the inner surface of the pipe with a shoe.

FIG. 10 is a schematic side view showing an example of an apparatus for integrally rolling a bead cutting tool on a pipe inner surface and a rolling roll to roll-smooth a welded portion.

[Explanation of symbols]

 1 ERW Steel Pipe 20 Water-cooled Mandrel 21 Cutting Bit 22 Pipe Internal Rolling Roll Unit 23 Pipe Internal Rolling Roll 24 Small Hydraulic Cylinder 25 Pipe Outer Backup Roll

Claims (2)

[Claims] 1. A method for removing an inner surface bead of a welded steel pipe produced by heating and pressure-welding both edges of an open pipe formed into a tubular shape, after supporting the outer surface of the pipe after cutting the inner bead with a cutting tool. A method for removing beads from an inner surface of a welded steel pipe, which comprises rolling and smoothing a cutting portion with a roll and a rolling roll movable in a pipe radial direction by a fluid pressure cylinder arranged in the pipe. 2. An apparatus for removing an inner surface bead of a welded steel pipe manufactured by heating and pressure-welding both edges of an open pipe formed into a tubular shape with an inner surface bead cutting mandrel having a cutting tool at the tip, At the tip of the pipe inner surface bead cutting mandrel, a roll unit having a pair of or more rolling rolls pressed in the pipe radial direction by a fluid pressure cylinder is mounted via a swing mechanism, and the roll unit has a water-passing structure. A bead removing device for an inner surface of a welded steel pipe, characterized in that cooling water is supplied through the mandrel and a backup roll is arranged on the outer surface of the pipe in a pair with the rolling roll of the roll unit.